Screw with cavity head



April 7, 1964 K. A. swANs'rRoM 3,127,919

SCREW WITH cAvITY HEAD Filed May e, 1959 2 sheets-sheet 1 IN VENTOR.

Qns RENTSVANSI ROM n/EV April 7, 1964 Filed May 6, 1959 K. A. SWANSTROM SCREW WTH CAVITY HEAD 2 Sheets-Sheet 2 l United States Patent Oiee 3,127,919l Patented Apr. 7, 1964 3,127,919 SCREW W111i CAVETY HEAD Klas Arent Swanstrorn, Doylestown, Pa., assigner to Penn Engineering @t lvianufaeturing Corporation. Doylestown, Pa., a corporation ot Pennsyivania Filed May 6, 1959, Ser. No. 811,495 9 Ciairns. (Ci. 151-41.73)

My invention is an improved self-clinching, headed stud and a method of securing same to thin shceted material. Such stud provides permanent fastening means by which other components may be secured to the sheet or panel by a nutor fastener threaded on to the end of the stud.

The construction of my improved stud is particularly adapted for use in comparatively soft panels, such as cold rolled steel, brass, copper, and aluminum alloys, and which are relatively thin, i.e., 1/16 of an inch or less, but may be used with relatively hard materials, such as stainless steel, which are in thin, sheeted form. The joinder between the stud and the sheeted material produces a ilushl head assembly which securely locks the stud into the sheeted material and results in high torque and pushout resistance.

It is recognized that the problem of securing bolts or studs to thin sheeted material presents special problems due to the thinness, and frequently softness, of the material with resulting ease of pull out or turning of the stud when a fastener is being secured to the projecting end of the stud. Previous efforts to secure a stud to a thin, sheeted material have frequently resulted in lthe buckling of the material in the vicinity of the head of the studatthe time the head is driven into the sheeted material.

An object of my invention is to provide a headed stud permitting a flush head assembly wtih a sheeted material or panel so that the head is securely locked in the sheet.

A further object of my invention is to provide quick andeasy means for securing the headed end of the stud in the sheeted material.

Itis a still further object of my invention to provide a headed stud which can be locked in a sheeted material Without buckling of the material in the vicinity of the stud head when the head is driven into the sheeted material.

A` still further object of my invention is to provide a stud that can be secured to sheeted material with high torquer and push-out resistance.

My improved self-clinching, headed stud comprises a head and an integral shank, the latter having a portion spaced from the head that is threaded to receive a fastener member. Between threaded portion of the shank and the head there are provided a pair of annular recesses one of which is designed to straddle and grip the under surface of the sheeted material. The head is preferably provided with spaced prongs on its under side which reach down to but not beyond the annular recesses on the stud.

The sheeted material to which the stud is to be secured is provided with a hole large enough to slidably receive the threaded portion of the stud. When the stud is dropped into the hole the head of the stud rests upon the upper surface of the sheeted material. An anvil having a central bore for receiving the threaded end of the stud is placed on the under side of the sheet so as to embrace the projecting portion of the stud. The anvil is also provided with an annular groove communicating with the central bore. When the anvil has been properly located and the stud has been inserted in the hole of the sheeted material, a punch is used to drive or squeeze the head of the stud into the sheeted material until the top of the head is llush with the top surface of thesheet. The punching or squeezing action securely imbeds the head in the sheet and `causes the material displaced by the head to iow into the annular recess and into the annular groove in the anvil thereby creating a liush head assembly having such resistance to movement in both radial or longitudinal directions as to usually require rupture of the sheet in order to move the stud.

The principles of my invention and the best mode in which I have contemplated applying such principles will further appear from the following description and the accompanying drawings in illustration thereof.

FIG. l is a side elevational view of the headed stud incorporating my invention;

FlG. 2 is a bottom view ofthe stud illustrated in FIG. l;

FIG. 3 is an enlarged fragmentary cross-sectional view of the portion of FIG. l that is encircled;

FIG. 4 is a view, partly in cross-section and partly in elevation, illustrating a stud constructed in accordance with my invention and located within a hole of sheeted material but prior to its being secured thereto and illustrating also the anvil and punch utilized in the securing operation;

FIG. 5 is a View similar to FIG. 4, showing the stud after it has been secured to the sheeted material;

FIG. 6 is a side elevational view of the stud and sheeted material after the anvil and punch have been removed;

FIG. 7 is an enlarged, cross-sectional view similar to FlG. 3 but illustrating a modied stud after it has been secured to the sheeted material; and

FIG. 8 is a side elevational view, similar to FIG. 6, but illustrating a stud with a modied head and resulting annular ring.

Referring to the drawings, FIG. 1 illustrates a selfclinching stud 10 having a head 12 and a depending integral shank 14, the major portion of the shank 14 being provided with threads 16 adapted to receive a fastener. Between the threads 16 and the head 12 are provided two annular undercut recesses or cavities 17, and 18, separated from each other by a crest 19, which receive displaced material 20 (FIG. 5) that ows when the stud 10 is permanently secured to a thin sheeted member 21.

The head 12 preferably includes spaced integral prongs 22 depending from the underside of a rim 23 on the head 12. The prongs 22 serve to increase the resistance of the stud to torque forces when the stud is secured to the sheeted member 21. The prongs 22 are arranged in an annular array extending radially outwardly (FIG. 2) from a conical central portion 24 Vof the head 12 that converges downwardly and that includes a at annular ring 25. The prongs have hat bottom surfaces 26 (that are substantially coplanar with the at ring 25) and vertical iiat and approximately radial parallel side walls 27.

The first or lower annular recess 17 is defined by a Wall approximately semi-circular or C shape in cross section, as illustrated by FIG. 3, and has a volume larger than the volume of the voids between adjacent threads 16 or the recess 18. The crest 2S, between the recess 17 and the threads 16, has a diameter approximately equal to the maximum diameter of the threads 16. The minimum diameter of the recess 1'7 is approximately equal to the root diameter of the threads. The height of the recess 17 is greater than the height of the voids between adjacent threads 16. The crest 19, between the recesses 17 and 18, has a maximum diameter less than the maximum diameter of the threads 16.

rThe second or upper recess 11S -is ideiinetd by an inclined or curved wall 29 and `the ring 25, as illustrated in FlG. 3. The minimum diameter or" the reiss 18 is located Iat Ithe juncture ou the curved wvall 29' .and the ring 1-25 and is approximately equal to the pitch diameter orf the threads 16. The exact shape of the wall Z9 may vary slightly, that is to say, it may include a substantially vertical upper porftion 29a, as illustrated in FIG. 3, or

3 comprise an entirely inclined wall 36, as illustrated in FfG. 7.

As illustrated in FlG. 5, `the recesses l' and 18 are proportioned and arranged relative to each other and the sheet metal plate Ztl so that a substantial portion of the axial width of the recess ll7 will lie partially below the lower surface 3l of the sheet 2l after the stud is secured 4to the sheet with the upper surface of the head l2 flush with the upper surface 32 of the sheet metal plate.

As viewed in FIG. 4, the stud is secured to the sheet 2l by first inserting the shank le through the hole 34. inthe sheet 2l. An anvil 35, provided with ta central bore 38 for receiving the threaded portion lo of the stud, is then positioned so that its face or upper surface 39 contacts the lower surface 3l of the sheet metal plate and is held in this position against movement by any suitable means. The anvil 3d is provided with an annular, square shouldered groove Il@ communicating `with the central bore 3S, hole 34 and the face 39.

'Ilhe vertical :dimension of lthe groove itl is such that, as illustrated in FIG. 5, vafter the head l2 is driven flush with the upper surface 32, the groove 4d encompasses a portion of the annular recess i7 but substantially none of `the shank below the lower recess i7, that is substantially none of the threads il@ are encompassed thereby.

Above the head l2 is positioned a suitable punch 44 which is driven downwardly by any suitable mechanism, the latter being well known and does not form part of this invention. The punch has a face to that is larger than the size of the head l2. so that the punch face E15 overlaps the portion of the sheet metal plate encompassing the stud head. Preferably, the face 45 is equal in size .to the face 39 of the anvil 36.

When the punch d4 is driven downwardly it in turn drives the head l2 into the sheet 2l countersinking it flush with the top surface 32 of the sheet. This action 'forces the material `of the plate 2d beneath the head l2 to flow downwardly and radially inwardly thereby completely filling the annular recess i8 and tilling, or substantially so, Ithe recess l'. That is to say, the sheet material Ztl below the prongs Q12 and the rim 2.3 is iorced to flow primarily downwardly into the recesses and, to a lesser degree, `annularly about the recesses. The small outside diameter of the crest 19, as compared with that of the crest 28, provides no impediment to the downward flow of displaced material. However, the crest 218 and `bottom of the 4groove itl does limit the downward iiow of material yand causes the material displaced by the prongs 22 to `flow .annularly about the groove itl and recess 17 resulting in `an annular boss t7 below the surface 3l of the sheet 2l.

The volume of the recesses i7 and 1S above the lower surface 3d is less than the volume of material displaced by the prongs 22, the ring 2.5, and .the rim 23. Likewise, the volume of that portion of the groove 4d that receives the flowing material is smaller than that of the material below the prongs 22 that is forced to flow downwardly below the surface Si.. Thus, the material .that flows past the surface 3l in excess of the volume of the groove Lit) directly below each prong 2Q. is forced by the walls delining the groove to to lio-w radially inwardly toward the shank ld entering the recess ll7` at spaced intervals about the periphery thereof and .tightly engaging the shank, as illustrated in FlGS. and 7.

Thus, after the anvil 3o has been removed, one sees (FlG. 6) below the surface 3l an irregular annular boss or bead 47 formed by a plurality of pods 4S disposed approximately below each of the prongs 22 and gaps 49 between the pods 453. The iiowing material completely iills all of the recess l?, and all of the recess ll7 above the lower surface 3l. The pods @Si are interconnected by `a ring 5l?, having portions including a lower looped surface Sl bowed upwardly between adjacent pods.

The depth .of the inter-connecting ring 5cl depends upon the spacing between the prongs 22. I-f the prongs are spaced very close to each other the pods 48 will be, of course, closer to each other, the length of the ring 5l) between pods d8 will be shorter than that illustrated in FIG. 6, and less of the recess d8 below the lower surface 3l of the -sheet metal plate will be gaped. The reverse will be true the prongs are spaced far apart from each other.

The ring and pod connection between the stud and the sheet is such as to offer very substantial resistance to forces generally parallel to the longitudinal axis of the .bolt (tending to separate the bolt from the sheet metal plate) by increasing the shear arca along which .the force is applied. lIhus, referring to FIG. 7, it is seen that by reason of the annular boss 47 the shear area is represented :by the dotted line which is much greater in extent than the shear area B, which extends from the bottom oi the prong 22 to the surface 3l. The B area would be the extent of the shear area if the recess 17 were terminated at the surface 3l. By utilizing the foregoing proportions and a C shape providing a root that is large in `comparison to the root `of the threads, the locked material that holds the stud to the sheet 2.1 is substantially in excess of that which would engage lthe shank if the threads were continued `all the way up the shank. Such large mass of connecting or locked material provides a strong and secure connection between .the sheet metal member and the stud as well as presenting a substantially transverse surface connection to any shearing force rather than an inclined surface connection, as in the case of a threaded connection.

Likewise, since the crest i9 of my stud is of a smaller diameter than the major :diameter of the threads and since the hole into which the stud is placed is preferably made .as small as possible, a space is provided between the crest 19 and the sheet 2l through which the liowing material may pass during the driving in of the head. Such space would not exist if the threads extended to the stud head since all the threads would have the same diameter. Such spacing is believed to be the reason that my stud does not buckle the sheet material, heretofore frequently found about clinch bolts of this type.

FlG. 8 illustrates a modification in which the spaced prongs 22 have been replaced by a solid member 52 equivalent to prongs Without any spaces therebetween. ln this embodiment, when the head 12 is driven into the sheet 2l, the head l2 forces ythe sheet material emcornpassing the shank to ow downwardly. This annular ring of ilowing material is guided inwardly by the walls of the groove di? to form a ring 55 depending `from the lower surface 31 which has the same depth throughout its periphery. Thus, in this embodiment the annular recess 17 becomes completely filled down to the lower surface 5d of the ring 55.

The shape of the head l2 may be that of a square, oval or hexagon rather than the round shape shown, if desired.

Having described my invention, I claim:

l. In combination, a sheeted material having first and second surfaces and a hole therethrough, a stud including a head and a shank, said shank extending through said hole, said shank having a threaded portion spaced from said head, said shank having first and second undercut recesses between said threaded portion and said head, said first recess being closer to said threads than said second recess, said head being driven into said sheet iiush with said first surface, a portion of the material of said sheet adjacent said stud being forced by said head to flow into said second recess and toward said first recess, the volume of said first recess being larger than the volume of said second recess, and an annular bead formed by the flowing material extending into said Iirst recess and projecting from said second surface.

2. ln combination, a sheeted material having top and bottom surfaces and a hole therethrough, a stud including a head and a shank, said shank extending through said hole, said shank having a threaded portion spaced from said head, said shank having first and second undercut annular recesses between said threaded portion and said head, said first recess being closer to said threads than said second recess, said head being driven into said sheet ush with the top surface thereof, a portion of the material of said sheet encompassing said stud being displaced and forced by said head to flow downwardly and radially inwardly toward said recesses, the volume of said first recess being larger than the volume of said second recess, and an annular bead encompassing and extending into a portion of said first recess and formed by said iiowing material, said bead depending from the bottom surface of said sheet metal body, and saidbead filling at least a portion of the first recess.

3. The structure recited in claim 2 wherein the volume of said recesses between the top and bottom surfaces of said sheet is less than the volume of the displaced material of said sheet.

4. A self-locking and countersinking stud including a head and a shank, said shank including a threaded portion and an unthreaded portion, the unthreaded portion being between the threaded portion and the head, said unthreaded portion being formed with two annular undercut recesses, the recess closest to the threaded portion being of larger volume than the other recess, a first crest separating said recesses, said first crest having an outside diameter smaller than the outside diameter of said threads, a second crest separating the recess of larger volume from the threads, said second crest having substantially the same outside diameter as the threads, the head displacing a volume of sheet metal material larger than the volume of the smaller of the recesses, whereby when said stud is driven into a sheet metal plate, the buckling of the plate is minimized due to the flow of displaced material in excess of the volume of the smaller recess into the larger recess after the first recess is filled.

5. The method of securing a stud including a head having depending prongs and a shank having undercut annular recesses adjacent said head to a sheet member having top and bottom surfaces comprising proportioning the recesses so that the lowest one straddles the bottom surface of said sheet member after said stud is secured to said sheet member, providing said sheet member with a bore for slidably receiving said shank, placing said stud in said bore with its head in contact with the top surface of said sheet member, providing an anvil with a central opening for receiving said shank and an annular groove communicating with said central opening and encompassing a portion of the lowest recess below the bottom surface of said sheet member after said stud is secured to said sheet member, placing said anvil in abutment With the bottom surface of the sheet member with said annular groove in communication with said bore in said sheet member, securing the anvil to resist a force to drive the head into the sheet member, and driving said head into said sheet member until it is flush with the top surface of the sheet member by use of a punch for securing said stud to said sheet member, said driving of the head into the sheet member causing the head to force a portion of the sheet material having a volume in excess of the volume of the recesses ultimately disposed between the top and bottom surfaces of the sheet member adjacent the stud to flow toward said recesses and groove, and said lowest recess becoming partially filled while said uppermost recess becomes entirely filled.

6. The method of securing a stud including a head having depending spaced prongs and a shank having two undercut annular recesses adjacent said head to a sheet member having top and bottom surfaces comprising proportioning the recesses so that the lower one straddles the bottom surface of said sheet member after said stud is secured thereto, providing said sheet member with a bore for slidably receiving said shank, placing said stud in said bore with its head in contact with the top surface of said sheet member, providing an anvil with a central opening for receiving said shank and an annular groove communicatingv with said central opening and encompassing a portion of the stud extending beyond the bottom surface of said sheet member, kplacing said anvil in abutment with the bottom surface of the sheet member, securing the anvil to resist a force to drive the headl into the sheet member, and driving said head into said sheet member until it is flush with the top surface of the sheet member by use of a punch for securing said stud to said sheet member, said driving of the head into the sheet member causing the head to force a portion of the sheet member in excess of the volume of said recesses and adjacent the stud to flow toward said recesses and groove, the upper recess becoming filled with sheet material and tightly engaged thereby, the lower recess becoming partially filled with an irregular annular bead, the irregularities being spaced from each other approximately the same distance as the spacing between said prongs.

7. A self-locking and countersinking stud including a head and a shank, said shank being divided into an undercut portion and a fastener means, the undercut portion being between the fastener means and the head, said undercut portion being formed with two annular undercut recesses, the recess closest to the fastener means being of larger volume than the other recess, a first crest separating said recesses, said first crest having an outside diameter smaller than the outside diameter of said fastener means, a second crest separating the recess of larger volume from the fastener means, said second crest having substantially the same outside diameter as the fastener means, the head displacing a volume of sheet metal material larger than the volume of the smaller of the recesses, whereby when said stud is driven into a sheet metal plate, the buckling of the plate is minimized due to the flow of displaced material in excess of the volume of the smaller recess into the larger recess after the first recess is filled.

8. In combination, a sheeted body having top and bottom surfaces and a bore therethrough, a drive-type fastener including a head and a shank, said head being driven into said sheeted body flush with one of said surfaces and displacing a portion of said sheeted body, said shank including fastener means spaced from said head, said shank also including two annular recesses formed in said shank between said fastener means and said head to accept material displaced only by said head, the recess spaced farthest from said head having a volume larger than the other recess and straddling one of said surfaces of said sheeted body, a crest separating the two recesses from each other, and a second crest separating the recesses from the fastener means, said first crest having a smaller outside diameter than said second crest, said second crest having a smaller outside diameter than the bore in said sheeted body, said head having a size and being driven into said sheeted body to such an extent relative to the volume of the recess closest to the head as to displace a volume of material in excess of the volume of the recess closest to the head, whereby the displacement of the sheeted body material is accomplished only by said head and not by either one of said crests when said head is driven into said sheeted body and a volume of sheeted body material is displaced in excess of the volume of the recess closest to the head and the excess material entering the recess farthest from the head.

9. The method of securing a stud including a head and a shank having undercut annular recesses adjacent said head to a sheet member having top and bottom surfaces comprising providing said sheet member with a bore for slidably receiving said shank, placing said stud in said bore with its head in Contact with the top surface of said sheet member, providing an anvil with a central opening for receiving said shank and an annular groove communieating with said central opening for encompassing a portion of said shank below the bottom surface of said sheet metal member, placing said anvil in abutment With the bottom surface of the sheet member with said annular groove in communication with said bore in said sheet member, securing the anvil to resist a force to drive the head into the sheet member, and driving said head into said sheet member until it is flush With the top surface of the sheet member by use of a punch and the lower annular recess straddles the lower surface of said sheet member, said head displacing toward the recesses during said driving a portion of the sheet member adjacent the stud in excess of the volume of the recess closest to the head to fill the latter with some of the displaced material and the remainder flowing into the farther recess and groove to minimize buckling of the sheet member 8 upon the driving of the head into the'sheet member for securing said stud to said sheet member.

References Cited in the le of this patent UNITED STATES PATENTS 1,919,552 Hasselquist July 25, 1933 2,078,212 Leighton Apr. `20, 1937 2,358,728 Miller Sept. 19, 1944 10 2,486,769 Watson Nov. 1, 1949 2,913,820 Barth Nov. 124, 1959 FOREIGN PATENTS 500,583 Canada Mar. 116, 1954 

2. IN COMBINATION, A SHEETED MATERIAL HAVING TOP AND BOTTOM SURFACES AND A HOLE THERETHROUGH, A STUD INCLUDING A HEAD AND A SHANK, SAID SHANK EXTENDING THROUGH SAID HOLE, SAID SHANK HAVING A THREADED PORTION SPACED FROM SAID HEAD, SAID SHANK HAVING FIRST AND SECOND UNDERCUT ANNULAR RECESSES BETWEEN SAID THREADED PORTION AND SAID HEAD, SAID FIRST RECESS BEING CLOSER TO SAID THREADS THAN SAID SECOND RECESS, SAID HEAD BEING DRIVEN INTO SAID SHEET FLUSH WITH THE TOP SURFACE THEREOF, A PORTION OF THE MATERIAL OF SAID SHEET ENCOMPASSING SAID STUD BEING DISPLACED AND FORCED BY SAID HEAD TO FLOW DOWNWARDLY AND RADIALLY INWARDLY TOWARD SAID RECESSES, THE VOLUME OF SAID FIRST RECESS BEING LARGER THAN THE VOLUME OF SAID SECOND RECESS, AND AN ANNULAR BEAD ENCOMPASSING AND EXTENDING INTO A PORTION OF SAID FIRST RECESS AND FORMED BY SAID FLOWING MATERIAL, SAID BEAD DEPENDING FROM THE BOTTOM SURFACE OF SAID SHEET METAL BODY, AND SAID BEAD FILLING AT LEAST A PORTION OF THE FIRST RECESS. 